The skin is a coating organ covering the body's surface. It is a vital organ enabling multiple functions such as sensing functions, protection from external aggressions, as well as immunological, metabolic, and thermoregulatory functions. These roles are made possible due to a complex structure including three distinct, superimposed layers: epidermis, dermis, and hypodermis. The epidermis is a coating epithelium that constitutes the external structure of the skin and provides its function of protection. This function is provided by the cohesion of epithelial cells and by the production of a filamentous and resistant protein, keratin.
The dermis is a connective tissue made up of a ground substance in which fibroblasts reside along with collagen fibers and elastin fibers, which are fibrous protein synthesized by fibroblasts. The collagen fibers ensure a great part of the solidity of the dermis; they take part in the elasticity and especially in the tonicity of the skin and/or the mucous membranes.
Below the dermis is a layer of adipose tissue: hypodermis, or subcutaneous tissue. The hypodermis includes a reserve fat layer, or white adipose tissue, attached to the lower part of the dermis by expansions of collagens and elastic fibers. The reserve fat layer consists of large vacuolated cells, the adipocytes, almost entirely filled with triglycerides. The volume of these cells can change rapidly, during a weight loss or weight gain, and can measure from 40 to 120 μm in diameter, which corresponds to a variation of 27 times in volume. The adipose tissue also contains connective tissue in which can be found, inter alia, particular fibroblasts and preadipocytes. The adipose tissue can store lipids as triglycerides or release them as fatty acids and glycerol.
Various conditions such as obesity, aging, and illnesses (e.g., HIV infection) can cause changes in body fat distribution which can result in abnormal and localized subcutaneous fat accumulation that can be disfiguring and, in some cases, cause impairment of breathing or other bodily functions. Numerous nonsurgical professed treatments, topical and non topical, are available today for alleged treatment of localized subcutaneous fat deposits. However, some of these professed treatments have a scientific, empiric base, and some a pseudoscientific base. Among the topical professed treatments, only the professed treatments delivered via intradermal injections of lipolytic compounds have achieved clinically satisfactory results. Topical treatments based on transdermal delivery of medications using methods other than percutaneous injections have a high rate of failure.